<style>
table { border: 5px solid blue;border-collapse: collapse;}
table.one {table-layout: automatic;}
table.two {table-layout: fixed;}
td {border: 3px solid black;}
</style>
<table class="one" width="100%">
<caption>table-layout: automatic;</caption>
<td width="20%">1000000000000000000000000000</td>
<td width="40%">10000000</td>
<td width="40%">100</td>
</table>
<br />
<table class="two" width="100%">
<caption>table-layout: fixed;</caption>
<td width="20%">1000000000000000000000000000</td>
<td width="40%">10000000</td>
<td width="40%">100</td>
</table>